A database is an organized way of storing, managing, and retrieving data across systems. Ease of access, structuring, and targeting make up for some uses of a good database.
A schema is a blueprint or structure of something.
What is a database schema?
A database schema is nothing but a structure or blueprint of a database, along with a set of rules to govern that database.
It’s like drawing a map. A map is your database; continents, countries, and cities are on that map. A schema’s job is to explain which city is within which country and which country is within which continent. It could do this using borders, labels, latitudes, and longitudes.
A database schema is used in the digital world for managing databases.
Every piece of information that we send or receive in the digital world is stored in a database, either physically or remotely.
The size of a database is directly proportional to the size of the data it houses.
Data is managed differently by different databases using different types of schemas.
Without a schema, data will simply exist meaninglessly without relationships or rules.
Why is a Database Schema important?
A database is made up of tables. Each table contains a specific type of information called fields. Each field has a data type. In database terminology, all these terms are also referred to as entities.
For example, let’s take a database called Map.
Such a database might have a table to store continent information with fields like
- continent ID
- continent name
- Continent location
Then there might be a table for countries with fields like
- country ID
- country name
- country location
And another table for cities with fields like
- City ID
- City name
- City location
Now, these three tables need to be able to communicate with each other, which can’t happen if their relationship with each other isn’t defined.
Without a schema, you won’t know that India and China are in Asia and Mumbai isn’t a continent.
A database schema’s role is to define these relationships and make them structured.
So a schema for this database would basically say, “There is a continent called Asia where India is a country with a city called Mumbai.”
How can I use the Database Schema?
A database schema can either be a visual representation or a bunch of formulas called integrity constraints.
These formulas are written in a data definition language called SQL.
Types of Database Schema
There are essentially three types of database schemas, namely:
- Logical Schema: This type defines all types of logical constraints, like entities, attributes, and views.
- Physical Schema: This type defines how the data is stored physically in a database, like files or indices.
- Conceptual Schema: Indicates a surface-level view of the database that includes details like how the information will be managed, what it will look like, and the business logic that ties everything together.
Here’s what a schema looks like for an e-commerce database.
Simply put, database schemas are used to define every database we directly or indirectly interact with. Moreover, these blueprints largely help construct scalable databases quickly and seamlessly.